Preheat oven to 350 degrees. Line a baking sheet with parchment paper and set aside.
In a small bowl, prepare an egg wash by beating the egg and water with a fork. Set aside.
Flour a large work surface and unroll the pie crusts. With a lightly floured rolling pin, roll the dough into a 1/8-inch thick rectangle. Cut the dough into fourteen Pop Tart shapes. The recipe yields seven pop tarts.
Using a pastry brush, brush the surface of each Pop Tart shape with the egg wash. Spoon 1-2 tablespoons of filling of your choice (fruit jam or brown sugar filling- See Filling Directions) in the middle of seven Pop Tart shapes, leaving enough room for a border to seal the Pop Tarts.
Place one Pop Tart sheet over each filling, until you have seven Pop Tarts in total. Use a fork to crimp the edges together to seal them shut on all sides.
Transfer the Pop Tarts to the prepared baking sheet. Bake for 21 minutes or until golden brown. Place the Pop Tarts on a wire cooling rack to cool before frosting.
Brown Sugar Filling (Optional): In a small bowl mix brown sugar, all-purpose flour, cinnamon, and melted butter until thoroughly combined. Set aside.
In a small bowl, stir together the powdered sugar, half-and-half, and vanilla until smooth. Add cinnamon if you're frosting the brown sugar Pop Tarts. If you're doing both flavors- frost the strawberry pop tarts first, then add the cinnamon to remaining frosting. To frost the pop tarts, use a spoon. Pour the frosting on the pop tart and allow the icing to flow naturally. Sprinkle your strawberry Pop Tarts with rainbow sprinkles. Enjoy!